I am not going to pretend to comprehend how they get in there. I do know if you want to catch bullheads the best ponds were ponds that had very recently been cleaned out. I also know of ponds that went been dry in the 80s and didn’t fill until the late 90s. My father claimed before they went dry they were awesome bass ponds. When they filled they were never stocked. However when a buddy of mine finally fished them the amount of 5 lbs+ bass that came out of the pair was amazing. They were at the top of the watershed with no nearby ponds out in the middle of the flint Hills.